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/* $Id: MemberInfoLinker.java,v 1.9 2004/11/20 15:41:24 eric Exp $
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* ProGuard -- shrinking, optimization, and obfuscation of Java class files.
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* Copyright (c) 2002-2004 Eric Lafortune (eric@graphics.cornell.edu)
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package proguard.obfuscate;
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import proguard.classfile.*;
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import proguard.classfile.visitor.*;
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* This ClassFileVisitor links all methods that should get the same names
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* in the name spaces of all visited class files. A class file's name space
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* encompasses all of its subclasses and interfaces. It is typically a class file
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* that is not being subclassed. Chains of links that have been created in
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* previous invocations are merged with new chains of links, in order to create
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* a consistent set of chains. Class initialization methods and constructors are
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* @see MemberInfoObfuscator
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* @author Eric Lafortune
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public class MemberInfoLinker
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implements ClassFileVisitor,
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// An object that is reset and reused every time.
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// The map: [class member name+descriptor - class member info]
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private final Map methodInfoMap = new HashMap();
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// Implementations for ClassFileVisitor.
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public void visitProgramClassFile(ProgramClassFile programClassFile)
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// Collect all members in this class's name space.
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programClassFile.hierarchyAccept(true, true, true, false,
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new AllMemberInfoVisitor(this));
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// Clean up for obfuscation of the next name space.
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methodInfoMap.clear();
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public void visitLibraryClassFile(LibraryClassFile libraryClassFile)
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// Implementations for MemberInfoVisitor.
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public void visitProgramFieldInfo(ProgramClassFile programClassFile, ProgramFieldInfo programFieldInfo)
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public void visitProgramMethodInfo(ProgramClassFile programClassFile, ProgramMethodInfo programMethodInfo)
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visitMethodInfo(programClassFile, programMethodInfo);
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public void visitLibraryFieldInfo(LibraryClassFile libraryClassFile, LibraryFieldInfo libraryFieldInfo)
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public void visitLibraryMethodInfo(LibraryClassFile libraryClassFile, LibraryMethodInfo libraryMethodInfo)
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visitMethodInfo(libraryClassFile, libraryMethodInfo);
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* Links the given method into the chains of links. Class initialization
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* methods and constructors are ignored.
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* @param classFile the class file of the given method.
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* @param methodInfo the method to be linked.
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private void visitMethodInfo(ClassFile classFile, MethodInfo methodInfo)
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// Private methods don't have to be linked.
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if ((methodInfo.getAccessFlags() & ClassConstants.INTERNAL_ACC_PRIVATE) != 0)
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// Get the method's original name and descriptor.
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String name = methodInfo.getName(classFile);
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String descriptor = methodInfo.getDescriptor(classFile);
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// Special cases: <clinit> and <init> are always kept unchanged.
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// We can ignore them here.
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if (name.equals(ClassConstants.INTERNAL_METHOD_NAME_CLINIT) ||
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name.equals(ClassConstants.INTERNAL_METHOD_NAME_INIT))
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// Get the last method in the chain.
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MemberInfo thisLastMemberInfo = lastMemberInfo(methodInfo);
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// See if we've already come across a method with the same name and
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String key = name + descriptor;
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MethodInfo otherMethodInfo = (MethodInfo)methodInfoMap.get(key);
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if (otherMethodInfo == null)
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// Store the new class method info in the map.
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methodInfoMap.put(key, thisLastMemberInfo);
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// Get the last method in the other chain.
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MemberInfo otherLastMemberInfo = lastMemberInfo(otherMethodInfo);
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// Check if both link chains aren't already ending in the same element.
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if (thisLastMemberInfo != otherLastMemberInfo)
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// Merge the two chains, making sure LibraryMethodInfo elements,
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// if any, are at the end of the resulting chain.
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if (thisLastMemberInfo instanceof LibraryMethodInfo)
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// This class method chain ends with a library class method.
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// Link this chain to the end of the other one.
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otherLastMemberInfo.setVisitorInfo(thisLastMemberInfo);
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/* We can skip this test and go straight to the final case.
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else if (otherLastVisitorAccepter instanceof LibraryMethodInfo)
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// The other method chain ends with a library class method.
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// Link the other chain to the end of this one.
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thisLastVisitorAccepter.setVisitorInfo(otherLastVisitorAccepter);
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// We have two non-library methods. Link their chains
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// one way or another.
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thisLastMemberInfo.setVisitorInfo(otherLastMemberInfo);
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// Small utility methods.
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* Finds the last class member in the linked list of class members.
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* @param memberInfo the given class member.
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* @return the last class member in the linked list.
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static MemberInfo lastMemberInfo(MemberInfo memberInfo)
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VisitorAccepter lastVisitorAccepter = memberInfo;
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while (lastVisitorAccepter.getVisitorInfo() != null &&
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lastVisitorAccepter.getVisitorInfo() instanceof VisitorAccepter)
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lastVisitorAccepter = (VisitorAccepter)lastVisitorAccepter.getVisitorInfo();
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return (MemberInfo)lastVisitorAccepter;
added
removed
src/proguard/obfuscate/MemberInfoLinker.java
